require "mathematical"

$blockRgx = /((?<block>\$\$[^\$]+\$\$)|[^\$](?<inline>\$[^\$]+\$)[^\$])/

module Jekyll
	class InlineLatex < Converter
		safe true
		priority :high

		def matches(ext)
			ext =~ /^\.md$/i
		end

		def output_ext(ext)
			".md"
		end

		def convert(content)
			# first pass
			buf = StringIO.new
			prev = 0
			renderer = Mathematical.new({:base64 => true, :format => :svg})
			content.to_enum(:scan, $blockRgx).map { Regexp.last_match }.to_enum.with_index.each do |match, i|
				if match[:block] != nil
					code = match[:block]
					a, b = match.offset(:block)
				else
					code = match[:inline]
					a, b = match.offset(:inline)
				end

				buf << content[prev..a].gsub(/^\$?\$/, "").gsub(/\$?\$$/, "")

				render = renderer.render(code)
				buf << "<img src='" + render[:data] + "' />"
				prev = b - 1
			end
			buf << content[prev..content.length].gsub(/^\$?\$/, "")
			return buf.string
		end
	end
end